1,219 research outputs found

    Multiple Sensory Modalities Used by Squid in Successful Predator Evasion Throughout Ontogeny

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    Squid rely on multiple sensory systems for predator detection. In this study we examine the role of two sensory systems, the lateral line analogue and vision, in successful predator evasion throughout ontogeny. Squid Doryteuthis pealeii and Lolliguncula brevis were recorded using high-speed videography in the presence of natural predators under light and dark conditions with their lateral line analogue intact or ablated via a pharmacological technique. Paralarval squid showed reduced escape responses when ablated; however, no differences were found between light and dark conditions in non-ablated paralarvae, as was previously shown in juveniles and adults, indicating that the lateral line analogue is integral for predator detection early in life. However, vision does play a role in survival because ablated squid in dark conditions had lower levels of survival than all other treatments. Throughout ontogeny, squid oriented themselves anteriorly towards the oncoming predator, maximizing sensory input to the lateral line analogue system and providing better positioning for tail-first escape jetting, the preferred escape mode. Ablated juveniles and adults had lower response times, escape velocities and peak acceleration than non-ablated individuals, indicating that the lateral line analogue enables squid to respond quicker and with more powerful jets to a predator and maximize escape success. Our findings reveal that the lateral line analogue plays a role in predator detection and successful escape response at the earliest life stages, and continues to contribute to successful evasion by aiding visual cues in juvenile and adult squid

    An Adaptive WTA using Floating Gate Technology

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    We have designed, fabricated, and tested an adaptive Winner-Take-All (WTA) circuit based upon the classic WTA of Lazzaro, et al [1]. We have added a time dimension (adaptation) to this circuit to make the input derivative an important factor in winner selection. To accomplish this, we have modified the classic WTA circuit by adding floating gate transistors which slowly null their inputs over time. We present a simplified analysis and experimental data of this adaptive WTA fabricated in a standard CMOS 2µm process

    Antisense Suppression of the Small Chloroplast Protein CP12 in Tobacco Alters Carbon Partitioning and Severely Restricts Growth

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    Abstract The thioredoxin-regulated chloroplast protein CP12 forms a multienzyme complex with the Calvin-Benson cycle enzymes phosphoribulokinase (PRK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). PRK and GAPDH are inactivated when present in this complex, a process shown in vitro to be dependent upon oxidized CP12. The importance of CP12 in vivo in higher plants, however, has not been investigated. Here, antisense suppression of CP12 in tobacco (Nicotiana tabacum) was observed to impact on NAD-induced PRK and GAPDH complex formation but had little effect on enzyme activity. Additionally, only minor changes in photosynthetic carbon fixation were observed. Despite this, antisense plants displayed changes in growth rates and morphology, including dwarfism and reduced apical dominance. The hypothesis that CP12 is essential to separate oxidative pentose phosphate pathway activity from Calvin-Benson cycle activity, as proposed in cyanobacteria, was tested. No evidence was found to support this role in tobacco. Evidence was seen, however, for a restriction to malate valve capacity, with decreases in NADP-malate dehydrogenase activity (but not protein levels) and pyridine nucleotide content. Antisense repression of CP12 also led to significant changes in carbon partitioning, with increased carbon allocation to the cell wall and the organic acids malate and fumarate and decreased allocation to starch and soluble carbohydrates. Severe decreases were also seen in 2-oxoglutarate content, a key indicator of cellular carbon sufficiency. The data presented here indicate that in tobacco, CP12 has a role in redox-mediated regulation of carbon partitioning from the chloroplast and provides strong in vivo evidence that CP12 is required for normal growth and development in plants.</jats:p

    Molecular genetic, life-history and morphological variation in a coastal warm-temperature sciaenid fish:Evidence for an upwelling-driven speciation event

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    The marine environment is punctuated by biogeographical barriers that limit dispersal and gene flow in otherwise widespread species (Teske et al., 2011a,b; Briggs & Bowen, 2012; Luiz et al., 2012). These barriers may be physical obstacles such as landmasses (e.g. Isthmus of Panama) or less intuitive features such as deep water (Lessios et al., 2003), freshwater outflows (Floeter et al., 2008) or oceanographic features (Shaw et al., 2004; Galarza et al., 2009; von der Heyden et al., 2011). Upwelling cells and sea surface temperature (SSTs) gradients in particular are known to disrupt gene flow, leading to divergence of allopatric populations and species (Waters & Roy, 2004; Teske et al., 2011a; Henriques et al., 2012, 2014, 2015). However, as oceanographic features are seldom permanent and frequently subject to considerable environmental variability, many barriers often permit some level of permeability to dispersal (Floeter et al., 2008). Other processes may influence the persistence of differentiated allopatric taxa across such physical barriers (Bradbury et al., 2008), with ecological divergence (and diversifying selection) being reported as a major evolutionary process influencing the biogeographical distributions of marine species (Pelc et al., 2009; Teske et al., 2011a; Gaither et al., 2015)

    Research ethics capacity building in Sub-Saharan Africa: a review of NIH Fogarty-funded programs 2000–2012

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    The last fifteen years have witnessed a significant increase in investment in research ethics capacity development throughout the world. We examine nine research ethics training programs that are focused on Sub-Saharan Africa and supported by the US National Institutes of Health. We collected data from grants awards' documents and annual reports supplemented by questionnaires completed by the training program directors. Together, these programs provided long-term training in research ethics to 275 African professionals, strengthened research ethics committees in 19 countries in Sub-Saharan Africa, and created research ethics curricula at many institutions and bioethics centers within Africa. Trainees' leadership resulted in new national systems and policies on research ethics, human tissue storage and export, and methods of monitoring compliance with research ethics guidelines. Training programs adapted to challenges that arose due to varied trainees' background knowledge in ethics, duration of time available for training, spoken and written English language skills, administrative obstacles, and the need to sustain post-training research ethics activities. Our report showcases the development of awareness of research ethics and building/strengthening of basic research ethics infrastructure in Sub-Saharan Africa. Nevertheless, the increasing amount and complexity of health research being conducted in Sub-Saharan Africa suggests the need for continued investment in research ethics capacity development in this region. This paper is part of a collection of papers analyzing the Fogarty International Center's International Research Ethics Education and Curriculum Development program

    Pregnancy incidence and correlates in a clinical trial preparedness study, North West Province South Africa.

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    INTRODUCTION: Women in HIV prevention trials often must typically agree to avoid pregnancy. Regardless, some become pregnant. Screening tools predicting pregnancy risk could maximize trial safety and efficiency. OBJECTIVES: We assessed incidence and correlates of pregnancy among women at high HIV risk. METHODS: We enrolled sexually-active, HIV-negative women into an observational cohort (2008-2011). At enrollment demographic, contraceptive, reproductive, pregnancy intention and behavioural data were collected. Women reported if one or both partners wanted or intended for the couple to become pregnant. We measured gender role beliefs using a locally validated eight-point index. We tested HIV and pregnancy, and inquired about sexually transmitted infection symptoms (STIs) at enrollment and monthly. HIV testing included behavioural counselling and condom provision, but did not specifically counsel women to avoid pregnancy. Cox proportional hazard modelling evaluated the associations with pregnancy. The multivariate model included the following variables "Recent pregnancy attempts", "Gender Roles Beliefs", "Self-reported STIs" and "Age". RESULTS: We screened 1068 women and excluded (24.6%, 263/1068) who did not report risk behaviour. Non-pregnant, non-sterilized women aged 18-35 (median = 21 years) enrolled (n = 438). Most women reported one partner (74.7%) and a prior live birth (84.6%). Median follow-up time was 6 months (range 0.7-15.5). Pregnancy incidence was 25.1 per 100 women-years (n = 57 pregnancies). Conservative beliefs on gender roles (Adjusted Hazard Ratio (aHR) 1.8; 95% confidence interval [CI] 1.1-2.9), recent pregnancy attempts (aHR 1.9; 95% CI 1.1-3.4) and baseline self-reported STI (aHR 2.5; 95% CI 1.4-4.4) were associated with increased incident pregnancy. Report of no pregnancy intention was associated with lowered pregnancy risk (aHR 0.3; 95% CI 0.1-0.7). CONCLUSIONS: We identified new and confirmed existing factors that can facilitate screening for pregnancy risk

    Long-cavity [Pd2L4]4+ cages and designer 1,8-naphthalimide sulfonate guests: rich variation in affinity and differentiated binding stoichiometry

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    One of the most appealing features of [Pd2L4]4+ cages is their well-defined cavities, giving binding affinity for specific guests. If seeking to bind larger and more complex guests, an attractive strategy is to lengthen the ligand backbone and therefore the inter-palladium(II) distance and cavity length. In comparison to large hollow [PdnL2n]2n+ polyhedra, this approach retains a well-ordered cavity environment. We report here a novel ligand, 1,3-bis(4-(4-ethynylpyridine)-phenyl)-adamantane, that has a hydrophobic bis(phenyl)adamantane core and forms [Pd2L4]4+ cages with a large 19 Å inter-palladium(II) cavity length. This cage binds long designer anions: naphthalimide sulfonates at ≥15 Å in length, which consist of two distinct domains: a naphthalimide and a phenyl sulfonate. This binding derives from hydrogen bonding between the endohedral pyridyl protons of the cage and the phenyl sulfonate group, and π–hydrophobic interactions between the adamantane core and the naphthalimide unit. The strength of binding depends on the degree of electron deficiency of the naphthalimide, brought about by the nature of substituents on this moiety, with binding constants for monoanionic guests ranging from 400 to 1800 M−1. The host/guest stoichiometry was found to be 1 : 2, unless the guest possessed a second sulfonate group, and was small enough to fit end-to-end within the cavity, in which case the stoichiometry was 1 : 1, and resulted in a high binding constant (for DMSO solvent) of 6100 M−1. This work demonstrates the subtle interplay and potential between cages and guests that are both large and that both have distinct dual zones able to interact with each other, and offers a pathway to specific and tunable binding of large guests.The authors would like to thank the University of Canterbury, the Australian National University, Massey University Albany and the University of Otago for funding. DP, KP and PK would like to thank the MacDiarmid Institute for funding. DP would like to thank the Royal Society of New Zealand for a Rutherford Postdoctoral Fellowship, and the Australian Research Council for a DECRA Fellowship

    A theory-based online health behaviour intervention for new university students (U@Uni): results from a randomised controlled trial

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    BACKGROUND Too few young people engage in behaviours that reduce the risk of morbidity and premature mortality, such as eating healthily, being physically active, drinking sensibly and not smoking. This study sought to assess the efficacy and cost-effectiveness of a theory-based online health behaviour intervention (based on self-affirmation theory, the Theory of Planned Behaviour and implementation intentions) targeting these behaviours in new university students, in comparison to a measurement-only control. METHODS Two-weeks before starting university all incoming undergraduates at the University of Sheffield were invited to take part in a study of new students' health behaviour. A randomised controlled design, with a baseline questionnaire, and two follow-ups (1 and 6 months after starting university), was used to evaluate the intervention. Primary outcomes were measures of the four health behaviours targeted by the intervention at 6-month follow-up, i.e., portions of fruit and vegetables, metabolic equivalent of tasks (physical activity), units of alcohol, and smoking status. RESULTS The study recruited 1,445 students (intervention n = 736, control n = 709, 58% female, Mean age = 18.9 years), of whom 1,107 completed at least one follow-up (23% attrition). The intervention had a statistically significant effect on one primary outcome, smoking status at 6-month follow-up, with fewer smokers in the intervention arm (8.7%) than in the control arm (13.0%; Odds ratio = 1.92, p = .010). There were no significant intervention effects on the other primary outcomes (physical activity, alcohol or fruit and vegetable consumption) at 6-month follow-up. CONCLUSIONS The results of the RCT indicate that the online health behaviour intervention reduced smoking rates, but it had little effect on fruit and vegetable intake, physical activity or alcohol consumption, during the first six months at university. However, engagement with the intervention was low. Further research is needed before strong conclusions can be made regarding the likely effectiveness of the intervention to promote health lifestyle habits in new university students. TRIAL REGISTRATION Current Controlled Trials, ISRCTN67684181

    Two-step stabilization of orbital order and the dynamical frustration of spin in the model charge-transfer insulator KCuF3

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    We report a combined experimental and theoretical study of KCuF3, which offers - because of this material's relatively simple lattice structure and valence configuration (d9, i.e., one hole in the d-shell) - a particularly clear view of the essential role of the orbital degree of freedom in governing the dynamical coupling between the spin and lattice degrees of freedom. We present Raman and x-ray scattering evidence that the phase behaviour of KCuF3 is dominated above the Neel temperature (T_N = 40 K) by coupled orbital/lattice fluctuations that are likely associated with rotations of the CuF6 octahedra, and we show that these orbital fluctuations are interrupted by a static structural distortion that occurs just above T_N. A detailed model of the orbital and magnetic phases of KCuF3 reveals that these orbital fluctuations - and the related frustration of in-plane spin-order-are associated with the presence of nearly degenerate low-energy spin-orbital states that are highly susceptible to thermal fluctuations over a wide range of temperatures. A striking implication of these results is that the ground state of KCuF3 at ambient pressure lies near a quantum critical point associated with an orbital/spin liquid phase that is obscured by emergent Neel ordering of the spins; this exotic liquid phase might be accessible via pressure studies.Comment: 13 pages, 3 figure

    Exploiting the labile site in dinuclear [Pd2L2]n+ metallo-cycles: multi-step control over binding affinity without alteration of core host structure

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    While Nature often controls supramolecular processes through regulation giving multiple levels of activity, synthetic metallosupramolecular systems have generally been binary (e.g. on/off) when they have control over molecular recognition events, and have often relied upon drastic chemical transformations or complete disassembly to enforce this control. We report here a new low symmetry ligand with a bidentate and a monodentate site (L). In combination with Pd2+, this ligand forms a [2 + 2] metallo-macrocycle, [Pd2L2L′2]n+, where L′ is the monodentate ancillary ligand that occupies the fourth and final coordination site of the metal ions. This assembly is structurally simple, but displays nuanced, multi-step binding affinity toward a neutral diplatinate guest employed for proof-of-concept. This complexity is introduced through varying the identity of L′, which can either be solvent (DMSO) or the halides chloride, bromide or iodide. The identity of L′ alters the cationic charge of the complex (neutral DMSO versus monoanionic halides) or otherwise influences the electron deficiency of the binding site of the host through varied strength of halide-ligand intra-molecular hydrogen bonding. Cycling between these different complexes was demonstrated, except for L′ = chloride which is non-reversible. This system therefore is able to interact with a platinate guest with four different graduations of affinity in response to stimuli, while still retaining the same simple core cationic structure. In addition to multi-setting binding affinity, we believe this is the first example of the use of variable intramolecular hydrogen bonding strength in switchable ancillary ligands to alter the electronic character and hence the π-π recognition characteristics of a metallosupramolecular host.DP would like to thank the ARC for a DECRA Fellowship, and the Royal Society of New Zealand for a Rutherford Postdoctoral Fellowship. BH would like to gratefully acknowledge the MBIE Catalyst Fund for a PhD scholarship. RV would like to thank the University of Otago for a PhD scholarship. The authors would like to thank the Australia National University, the University of Canterbury, the University of Otago, and the MacDiarmid Institute for additional funding. The authors acknowledge the contribution of the NeSI high performance computing facilities to the results of this research. New Zealand’s national facilities are provided by the New Zealand eScience Infrastructure and funded jointly by NeSI’s collaborator institutions and through the Ministry of Business, Innovation & Employment’s Research Infrastructure program. https://www.nesi.org.nz
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